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Abstract

Background and objective: Probiotics offer beneficial impact to human health, including lowering serum cholesterol and decreasing occurrence of intestinal infections as well as conferring anti-carcinogenic activities to foods. The present study assessed probiotic doogh drinks made from camel milk and stability of Lactobacillus acidophilus LA-5 (free or microcapsulated) during product shelf life at refrigerated temperatures as well as at simulated gastrointestinal conditions.

Material and methods: Microcapsules of Lactobacillus acidophilus LA-5 were produced through coacervation of gelatin and high-methoxy pectin (esterification degree of 70%) or gelatin and Arabic gum as wall materials. Stability of probiotic bacteria in gastrointestinal simulated conditions was assessed. Sensory acceptance of samples was investigated using Hedonic test (9-points) during cold storage for 35 days.

Results and conclusion: After 35 days of cold storage, doogh samples included Lactobacillus acidophilus LA-5 microcapsulated by gelatin- pectin and gelatin-Arabic gum had more survival (77.11 and 74.19%, respectively) than free cells (62.34%). As bacteria subjected to simulated gastric juice, the bacterial logarithmic population of free, gelatin-pectin and gelatin-Arabic gum microcapsulated Lactobacillus acidophilus LA-5 reached to 4, 6 and 5, respectively. In the case of exposure to simulated intestinal fluid, logarithm of the bacterial population reached to 5.6, 6.5 and 6.2 for free, gelatin-pectin and gelatin-Arabic gum bacterial microcapsules, respectively. Organoleptic assessment showed no significant differences between samples in terms of aroma, appearance and overall acceptance. As a result, doogh produced from camel milk containing gelatin-pectin and gelatin-Arabic gum microcapsules of Lactobacillus acidophilus LA-5 included a further cold storage stability, compared to that containing free bacteria. Furthermore, a final probiotic population of more than 106 were seen for microcapsules in simulated intestinal fluid.